Meredith would at least try to keep tabs on the other people of note in the city. She wouldn't be very good at the game if she didn't know who all the players were.
Meredith herself probably has something of a reputation. I imagine she usually has agents meet with people rather than meeting them herself, to preserve some level of anonymity. It's easier to spy on people when they don't know your face, after all.
If she does meet someone in person for business, its generally with a disguise on to conceal her identity.
Still, its very possible at least some of the characters have met her, or at least know of her. She may have done work for some of the nobles... or perhaps even done work against them.
As for the characters of more humble origins, Meredith does do what she can to help the poor and the helpless, so perhaps her paths crossed with characters in that regard somehow.